In each postal sorting office, a mail processing apparatus is provided. The mail processing apparatus detects postal indicia such as stamps from mail items, and sorts faces and up-and-down directions of mail items based on the detection results of the postal indicia. For example, many stamps include afterglow components. The mail processing apparatus detects afterglow components from mail items and can detect stamps using the detection results of the afterglow components. The mail processing apparatus registers stamp images in advance, and can detect stamps from mail items based on the registered stamp images.
Mail items handled by the aforementioned mail processing often include picture cards. On a specific face of each picture card, a picture, photo, or pattern is printed. The aforementioned mail processing apparatus may often erroneously detect a part of the picture, photo, or pattern on the specific face of a picture card as a non-registered stamp having no afterglow component. Due to such detection errors of postal indicia, the mail processing apparatus cannot often normally sort picture cards. That is, such detection errors cause a sorting performance drop of the mail processing apparatus.
On the other hand, a mail processing apparatus which can efficiently recognize picture cards has been disclosed. For example, when a character string (e.g., “Printed in”) unique to a picture card is detected from a mail item, this mail processing apparatus detects this mail item as a picture card.
Although the mail processing apparatus which can efficiently recognize picture cards has been disclosed, as described above, it is still difficult to prevent the aforementioned detection errors of postal indicia. That is, it is difficult to improve the sorting performance of mail items unless detection errors of postal indicia can be reduced.